Device for driving day and date indicators in a wrist-watch

ABSTRACT

A watch having a driving device for a day indicator and for a date indicator, which device comprises a calenderwheel for rotating at a rate of one revolution every 24 hours, a cam and a shifting member rigidly coupled to one another and rotatively supported coaxially to the calendar-wheel, a pin integral with the cam and engaging an elongated and arcuate aperture of the calender-wheel for coupling the wheel and the cam in such a way that the cam and the shifting member are able to rotate freely through a certain angle with respect to the wheel, a control member cooperating with a spring and with the cam, so as to brought progressively into a shifting position and then for shifting the cam abruptly, the shifting member having a shifting element which describes during the shift a path passing beyond the point of rotation of the cam, a banking element which strikes against a concentric portion of the cam at the conclusion of the shift, and the shifting member further comprises a drive element for the date indicator and at least one drive element for the day indicator.

United States Patent 1 Jakob [4 1 May 13, 1975 DEVICE FOR DRIVING DAY AND DATE INDICATORS IN A WRIST-WATCH Edwin Jakob, Grenchen, Switzerland [73] Assignee: ETA Ebauches Fabrik, Grenchen,

Switzerland [22] Filed: May 29, 1974 [21] App]. No.: 474,348

[75] Inventor:

[30] Foreign Application Priority Data Primary ExaminerGeorge H. Miller, Jr. Attorney, Agent, or FirmStevens, Davis, Miller & Mosher [5 7] ABSTRACT A watch having a driving device for a day indicator and for a date indicator, which device comprises a calenderwheel for rotating at a rate of one revolution every 24 hours, a cam and a shifting member rigidly coupled to one another and rotatively supported coaxially to the calendar-wheel. a pin integral with the cam and engaging an elongated and arcuate aperture of the calender-wheel for coupling the wheel and the cam in such a way that the cam and the shifting member are able to rotate freely through a certain angle with respect to the wheel, a control member cooperating with a spring and with the cam, so as to brought progressively into a shifting position and then for shifting the cam abruptly, the shifting member having a shifting element which describes during the shift a path passing beyond the point of rotation of the cam, a banking element which strikes against a concentric portion of the cam at the conclusion of the shift, and the shifting member further comprises a drive element for the date indicator and at least one drive element for the day indicator.

6 Claims, 3 Drawing Figures PATENTED HAY I 3 I975 SHEET 18F 3 PATENTED MAY 1 3 m5 SHEU 2 (I? .3

1 DEVICE FOR DRIVING DAY AND DATE INDICATORS IN A WRIST-WATCH This invention relates to a device for driving day and date indicators in a wrist-watch, comprising a calendarwheel rotating at the rate of one revolution every 24 hours, a cam coupled to the calendar-wheel in such a way as to be able to rotate freely with respect to this wheel through a certain angle, and a control member cooperating with an incline of the cam in order to cause the cam to rotate abruptly through the said angle.

instantaneously advancing calendar mechanisms are already known which display the day of the week and the date, and which comprise one or two control members which pivot or slide or effect a combined motion of translation and rotation. This or these control members are equipped with several auxiliary members acted upon by springs and operating in the vicinity of the day and date indicators.

These known devices advance the day and date indications by jumps. However, they are relatively complicated in their construction, besides being laborious and delicate to assemble.

Other known devices are simpler, but they have the drawback of changing the day and/or date indication by means of a slow rotation of the corresponding member.

It is the object of the present invention to provide a device of the above-mentioned type which advances the day and date indications by instantaneous jumps, which is of a simpler construction than the known devices of that type, and which is also easier to assemble.

To this end, in the device according to the present invention, the control member comprises a shifting element which cooperates with the incline of the cam, and a banking element separate from the shifting element, the shifting element describing during the shift a path passing beyond the point of rotation of the cam, while the banking element strikes against a concentric portion of the cam at the conclusion of the shift.

Other objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a plan view of the preferred embodiment, the part being shown in the position they occupy just before the spring begins to be wound,

FIG. 2 is a plan view of the same elements immediately after the shift, and

FIG. 3 is a section through the device.

FIG. 1 shows an hour-wheel 1 which drives a calendar-wheel 3 via a step-down wheel 2. The calendarwheel 3 rotates clockwise, as indicated by an arrow 4, at the rate of one revolution every 24 hours.

As illustrated in FIG. 3, the wheel 3 pivots freely on an arbor 5, the lower end of which is mounted in a bearing (not shown) borne by the plate. The arbor 5 carries a cam 6 riveted on a cylindrical bearing surface thereof. A stud '7 projecting from the cam 6 passes through an elongated aperture 12 of the calendarwheel 3 and enters a recess 14 of a shifting member 13. This member 13, consisting of a blanked and bent metal plate, also pivots freely on the arbor 5. It is held axially by the head of the arbor 5, so that the elements 5, 13, 3 and 6 form an assembly unit. The shifting member 13 is coupled directly to the cam 6 by the tenon 7, and these two members can rotate together with respect to the wheel 3 about its axis through a maximum angle of 180, which corresponds to the length of the arcuate slot 12.

In the embodiment described here, the periphery of the cam 6 includes a concentric arcuate portion 10 which extends over approximately 220 and with which a portion of a lever 8 can enter into contact. The lever 8 is acted upon by a spring 9 and pivots about a pin 8a. The shifting member 13 has three fingers 15, 18, and 19 distributed along its periphery. The two fingers 18 and 19 are bent upwards and engage in teeth 20 of a day-star 21, while the finger 15, which extends in the same plane as the rest of the member 13 and is wider than the fingers 18 and 19, cooperates with teeth 16 of a date-ring 17.

In FIG. 1, the cam 6 is in its starting position defined by the particular orientation of its arcuate portion 10 and by the fact that a corresponding portion 11 of the lever 8 presses against it under the influence of the spring 9. One end 24 of the portion 11 of the lever 8 is situated in front of a portion 26, shaped as an arc of a spiral, of the cam 6, while the other end 23 is convex and is in contact with a shoulder 22 of the cam 6.

This arrangement makes it possible to increase the angle, through which the cam 6 rotates under the influence of the lever 8 when the portion 24 follows the incline 26, from to --the maximum which has been obtained with the prior art devices-- up to about ll5. This wide angle of rotation enables the shifting member 13 to shift'the day-star 21 through an angle corresponding to two steps of its toothing 20, as will be seen further on.

The device operates as follows:

The hour-wheel 1 actuates the calendar-wheel 3 clockwise, as designated by the arrow 4, via the wheel 2. According to the position of the wheel 3, it may freely describe a more or less long path before the end of the aperture 12 strikes against the stud 7 of the cam 6 (FIG. 1).

When the wheel 3 continues to rotate in the direction of the arrow 4, its rotating motion is transmitted by the stud 7 to the cam 6 and to the shifting member 13, and the arbor 5 also rotates since it is integral with the cam 6. The calendar-wheel 3, mounted as a functional unit,

starts to operate as a rigid wheel as soon as that coupling has been effected. The portion 22 of the cam 6 strikes against the'portion 23 of the lever 8, which gradually pivots counter to the influence of the spring 9, winding it as the radius of the cam 6 increases.

If the portion 22 of the cam 6 is considered as a tooth of a pinion coaxial with the arbor 5, and the portion 23 of the lever 8 is considered as an inner tooth of a wheel having its center at 8a, then it will be seen that the portion 22 rolls on the portion 23. This rolling takes place along a relatively short path before the center line defined by the straight line 5-8a is reached, and along a longer path beyond that line. This transmission of force, quite analogous to that found in an involute gearing, ensures very high mechanical efficiency as compared with the known calendar systems utilizing a cam. Thus it is possible to trace the profiles in such a way that the spring 9 winds tightly during the first phase of winding, i.e., while the rolling is taking place, without any exaggerated loss of amplitude. Hence in the second phase of its winding, where there is friction between the cam 6 and the portion 23 of the lever 8, the spring 9 undergoes only a slight further increase in its rate of winding, which is likewise favorable from the point of view of the loss of amplitude of the balance. At the outset, only the portion 22 is in contact with the portion 23. Upon the subsequent rotation of the wheel 3, the portions 23 and 24 of the lever 8 are in contact with the cam 6. Thereafter, the contact is limited to the portion 24.

FIG. 2 shows the relative positions of the lever 8 and the cam 6 immediately before the shift. In this location, the cam 6 exhibits its maximum radius, and the spring 9 has reached its maximum state of winding.

When the wheel 3 continues to rotate in the direction of the arrow 4, an edge 25 of the lever 8 slides on the impulse surface or incline 26 of the cam 6. The force of the spring 9 acting upon the lever 8 causes a rotating motion of the cam 6, so that the spring 9 relaxes abruptly, and the cam 6 and the shifting member 13, by a rapid rotating movement, instantaneously assume the positions shown in FIG. 1. The finger actuates the date-ring 17 by one step of the toothing 16, and the two fingers l8 and 19 actuate the day-star 21 by two steps of its toothing 20. The new positions of the members 17 and 21 are fixed by springs 27 and 28. The wheel 3 remains stationary during the shift, for the stud 7 moves only within the aperture 12 provided for that purpose.

Thus the shifting of the day and the date takes place instantaneously through a rotating movement of the shifting member 13 coaxial with the calendar-wheel 3. This-arrangement ensures the synchronized change of the display of the day and of the date. The rear sides of the shifting fingers l5 and 19 act as blocking elements to prevent an exaggerated jump of the indicator members. Under the influence of the acquired energy, these members do, in fact, have a tendency to jump beyond the positions ensured by the springs 27 and 28, but the fingers l5 and 19 act as resilient shock-absorbers. The residual energy due on the one hand, to the inertia of the cam 6, the arbor 5, the shifting member 13, and on the other hand, to the displacement of the lever 8, prolongs the clockwise movement of the member 13. It rotates through an additional small angle, which again tenses the spring 9 somewhat until the equilibrium of forces has been re-established. The spring 9 then returns the cam 6 and the shifting member 13 to the starting position (FIG. 1), via the lever 8. The wheel 3 rotates alone after the shift until, after several hours, the end of the aperture 12 strikes against the stud 7 and reassumes the position shown in FIG. 1.

The device described presents numerous advantages:

1. Fewer parts to be assembled as compared with conventional devices since the combined shifting member is directly mounted coaxially on the calendarwheel;

2. less space taken up inasmuch as the shifting member mounted on the calendar-wheel may be sunk with it into the plate;

ticularity is feasible owing to the special shape of the cam and of the lever actuating it, as well as through the shifting member disposed coaxially with the wheel and having two shifting fingers for the day of the week.

What is claimed is:

1. A watch including day and date indicators, and a device for driving the day and date indicators, comprising a calendar-wheel for rotating at the rate of one revolution every 24 hours, a cam coupled to the calendarwheel in such a way as to be able to rotate freely with respect to the said wheel through a certain angle, and a control member cooperating with an incline of said cam for causing the cam to shift by rotating abruptly through said angle, wherein'the control member comprises a shifting element which cooperates with the incline of the cam, and a banking element separate from said shifting element, the shifting element describing during the shift a path passing beyond the point of rotation of the cam, while the banking element strikes against a concentric portion of the cam at the conclusion of the shift, and a shifting member which is coupled rigidly to the cam and has a drive element for the date indicator and at least one drive element for the day indicator.

2. A watch in accordance with claim 1, wherein the day indicator comprises seven teeth or a multiple of that number, and wherein the shifting member comprises a number of drive elements dependent upon the number of teeth of the day indicator, said drive elements taken together for causing the day indicator to advance by one-seventh of a revolution at each shift.

3. A watch in accordance with claim 1, wherein the control member is a lever acted upon by a spring.

4. A watch in accordance with claim 3 wherein the banking element consists of an arcuately blanked portion of the edge of the said lever.

5. A watch in accordance with claim 4, wherein the said banking element extends between the shifting element and a convex end of the said lever, and wherein the said convex end cooperates with a radially oriented portion of the cam.

6. A watch in accordance with claim 5, wherein the said radially oriented portion of the cam and said convex end are blanked as segments of an involute, and roll upon one another when the cam is actuated by the calendar-wheel. 

1. A watch including day and date indicators, and a device for driving the day and date indicators, comprising a calendar-wheel for rotating at the rate of one revolution every 24 hours, a cam coupled to the calendar-wheel in such a way as to be able to rotate freely with respect to the said wheel through a certain angle, and a control member cooperating with an incline of said cam for causing the cam to shift by rotating abruptly through said angle, wherein the control member comprises a shifting element which cooperates with the incline of the cam, and a banking element separate from said shifting element, the shifting element describing during the shift a path passing beyond the point of rotation of the cam, while the banking element strikes against a concentric portion of the cam at the conclusion of the shift, and a shifting member which is coupled rigidly to the cam and has a drive element for the date indicator and at least one drive element for the day indicator.
 2. A watch in accordance with claim 1, wherein the day indicator comprises seven teeth or a multiple of that number, and wherein the shifting member comprises a number of drive elements dependent upon the number of teeth of the day indicator, said drive elements taken together for causing the day indicator to advance by one-seventh of a revolution at each shift.
 3. A watch in accordance with claim 1, wherein the control member is a lever acted upon by a spring.
 4. A watch in accordance with claim 3 wherein the banking element consists of an arcuately blanked portion of the edge of the said lever.
 5. A watch in accordance with claim 4, wherein the said banking element extends between the shifting element and a convex end of the said lever, and wherein the said convex end cooperates with a radially oriented portion of the cam.
 6. A watch in accordance with claim 5, wherein the said radially oriented portion of the cam and said convex end are blanked as segments of an involute, and roll upon one another when the cam is actuated by the calendar-wheel. 